STRATEGIES TO IMPROVE POSTFLOWERING DROUGHT TOLERANCE IN RABI SORGHUM FOR PREDICTED CLIMATE CHANGE SCENARIO

摘要

The experiments were conducted during rabi seasons of 2007-08, 2008-09 and 2009-10 to screen the promising germplasm, advanced breeding lines and landraces to identify the new sources and traits associated with postflowering drought tolerance in sorghum. The crop was sown under irrigated and un-irrigated condition to examine the potential of sorghum genotypes to adapt to the postflowering drought. Improved sources (PEC 17, EP 87, EP 57, SLB 9, SLR and RSLG 262) for postflowering drought tolerance have been identified in terms of higher grain yield, biomass and green leaf area retention. Significant and positive relationships of SPAD chlorophyll meter reading (SCMR) with total dry mater (R2=0.67) and grain yield (R2=0.42) suggests that selection using SCMR will have 42-67% probability in selecting genotypes with higher total dry mater and grain yield. Most appropriate stage to screen for postflowering drought tolerance on the basis of green leaf area retention (stay green trait) is around 30 days after flowering. Specific leaf weight (SLW) increased significantly under un-irrigated as compared to irrigated conditions in all the genotypes suggesting increase in leaf thickness under moisture stress conditions. Positive relationships between percent increase in SLW under stress conditions and yield components indicate that increase in leaf thickness is an important adaptive trait to postflowering drought. These results concludes that SCMR can be used as a surrogate measurement of staygreen trait andincrease in SLW under residual moisture conditions is a potential selection criteria for postflowering drought tolerance in rabi sorghum.